This disclosure relates generally to oil and gas well production and more particularly, to a actuator apparatus for downhole completion tools.
There are an abundance of well tools, such as valves, packers, chokes, etc. that are inserted downhole in an oil and gas well and are controlled from the ground surface to perform various functions such as, for example, controlling the flow of production fluid from a reservoir to a storage unit at the ground surface.
Failure of these type tools requires that the well be reentered to mechanically repair, adjust, or shift, the tool. This is very costly, and often poses environmental risks, especially in connection with a marine well such as a sub-sea well. Consequently, an important industry goal is to eliminate, or at least reduce or delay, the need for intervention.
Current systems use either electrical or hydraulic power to provide sufficient force to operate the well tools. Thus, a loss of fluid pressure in a hydraulically driven actuator, or a loss of electrical power to an electrically driven actuator, would at least temporarily, and perhaps permanently, disable all the tools that are actuated by that system, possibly requiring intervention.
Therefore, what is needed is a method and apparatus for increasing the reliability of well tools, and avoiding the limitations inherent in a single actuator system.